Sequential flasher

ABSTRACT

A sequential flasher includes a plurality of successive stages connected in cascade and each including a PNP transistor, having its emitter connected to the positive terminal of a source of potential, and an NPN transistor. Each stage includes a first loop constituted by the emitter of the PNP transistor, a resistor connecting the base thereof to the collector of the NPN transistor, and a resistor and a condenser connected in series between the base of the NPN transistor and the collector of the PNP transistor. A second loop is constituted by a resistance connecting the emitter of the NPN transistor to the junction of the resistor and the condenser. Each stage has a respective load connected between the collector of its PNP transistor and the negative terminal of the source. The collector of each PNP transistor, except that of the last stage, is connected to the emitter of the NPN transistor of the next succeeding stage, with the collector of the last PNP transistor being connected to the emitter of the NPN transistor. The resistance may be a resistor or may be a diode. A starting condenser is connected in at least the first stage.

I United States Patent 1 1 3,560,769

[72] Inventors Tetsuji Shimizu; 3248,558 4/l966 Seif r .i 307/273XSusumu Usami. Nagoya, Japan 3378,693 4/1968 Schmidt 307/273X 1968Primary Examiner lohn S. Heyman Patented Feb 197] AttorneyMcGlew andToren [73] Assignee Kabushiki Kaisha Tokai Rika Denki sejsakushmNishikasugai-E ABSTRACT: A sequential flasher includes a plurality of wev Alchi'prefectul'ev Japan cessive stages connected in cascade and eachincluding a PNP Pflomy 1967 transistor. having its emitter connected tothe positive ter- Japan minal of a source of potential, and an NPNtransistor. Each 42/39022 stage includes a first loop constituted by theemitter of the PNP transistor, a resistor connecting the base thereof tothe 54] SEQUENTIAL FLASHER collector of the N PN transistor, and aresistor and a condenser 4 Claims 2 Dra Fi 5 connected In series betweenthe base of the NPN transistor wmg g and the collector of the PNPtransistor. A second loop con- [52] US. Cl 307/293, stituted by aresistance connecting the emitter of the NPN /223, 307/273, 307/2 88; 321 2 9/ 331 transistor to the junction of the resistor and the condenser.[5 ll Int- Cl H03k 17/28, Each stage has a respective load connectedbetween the col H03k 23/08 lector of its PNP transistor and the negativeterminal of the Field of Search 307/273, ource The collector of each PNPtransistor, except that of 288, 2 3, 2 340/331 the last stage, isconnected to the emitter of the NPN transistor of the next succeedingstage, with the collector of [56] References C'ted the last PNPtransistor being connected to the emitter of the UNITED STATES PATENTSNPN transistor. The resistance may be a resistor or may be a 3,244,9064/1966 Goering 307/273X diode. A starting condenser is connected in atleast the first 3,244,909 4/1966 Henderson 307/273X stage.

SEQUENTIAL FLASI-IER The present invention relates to a sequentialflasher energizing and deenergizing successively and automaticallyelectric bulbs, lamps, or relays, serving as loads provided in aplurality of stages or circuits. and effecting cyclically andrepetitively this operation.

Most conventional sequential flasher flashers of this type haveincorporated mechanical means, such as snap action switches operated insuccession by means of cams of different configurations provided on thereduced speed output shaft of DC permanent magnetic field-type motor.The sequential flasher of the present invention has basically adifferent system from the conventional flasher and employs no mechanicalswitch means.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings show apreferred embodiment of sequential flasher of the present invention,wherein;

FIG. I is a circuit diagram of a sequential flasher of the presentinvention; and

FIG. 2 is a partial circuit diagram illustrating a modification of theflasher shown in FIG. 1.

In the preferred embodiment of sequential flasher of the presentinvention, the sequential flasher is constituted by a plurality ofstages or circuits W1, W2, W3, Wn arranged in cascade connection andeach including a feedback loop or feedback circuit incorporating aPNPtype transistor Tra, whose base is connected to a collector of anNPN-type transistor Trb through a resistor Rb and whose collector isconnected to the base of the NPN transistor through a condenser C, andresistor Rc. The emitter of each NPN transistor is connected to thejunction between the associated condenser C and the associated resistorRc, through a diode D. The several stages have respective load L1, L2,L3, Ln, such as electric bulbs, lamps, or relays, interconnected betweencollectors of the respective PNP transistors and the negative terminalof the potential source. In addition, the several stages areinterconnected through lines 11, 12, I3, which connect the collectors ofeach PNP transistor to the emitter of the PNP transistor of the nextsucceeding stage, except for the last stage. In the last stage Wn, thecollector of the PNP transistor is connected to the emitter of the PNPtransistor of the first stage through line In. A starting condenser C2is connected in parallel with the collector-emitter circuit of the PNPtransistor of the first stage. A control switch S is provided to connectthe flasher to the source of potential. Also, each stage has arespective resistor Ra for protecting the transistors thereof withrespect to temperature and voltage.

A diode D, in the present invention, may be substituted by a resistor.The starting condenser Cs may be connected in a manner as shown in FIG.2.

The sequential flasher of the present invention operates as follows.When starting switch S is closed the base current of the transistor tralflows through the resistor Rbl of the first stage W1, the startingcondenser Cs and the load Ln of the terminal stage to raise thecollector potential of transistor Tral. Consequently,-the base currentfor the transistor Trbl flows through the condenser C l, resistor Rcland the load Ln of the terminal stage Wn to increase the collectorcurrent of transistor Trbl. By this, the collector potential of thetransistor Tral rises still more. With such continuous and repetitivecurrent flow, the transistor Tral is rapidly brought into fullconduction to energize the load L1. Then, the condenser Cl becomes fullycharged, and its charging current is reduced. The charging of condenserCl, at this time, is effected by the voltage of potential source. On theother hand, immediately the transistor Tral comes into conduction, thetransistor Trbl is reversely biased to be rapidly turned into thenonconductive or blocking state to deenergize the load L1. With thefirst stage W1 being kept in operation, the collector potential of thetransistor Tral increases to a value substantially equal to the voltageof the potential source. Then, charging a condenser C2 of the secondstage W2 is effected at its terminal connected to the diode D2, througha loop including transistor Tral, diode D2, condenser C2, load L2 andthe negative terminal of the potential source. During charging of thecondenser, transistors Tra2 and Trb2 remain nonconductive, since theemitter of transistor Trb2 is connected to the collector of transistorTral of the preceeding stage. Thus, no current flows between transistorsTral and Tra2.

However, immediately as the first stage WI becomes inoperative, asdescribed, the charge stored in the condenser C2 flows into the base ofthe transistor Trb2 through the resistor RC2, thereby putting transistorTrb2 into the conductive state. Thus, the transistor Tra2 is broughtinto conduction to energize the load L2. After a certain time interval,the second stage becomes nonconductive to deenergize the load L2, in amanner similar to the first stage W1. In synchronism with deenergizationof the L2, the h third :stage W3 becomes to operation to energize theload L3, in the same way as described for the second stage W2. In themanner as described, the loads L1, L2, L3, Ln are energized anddeenergized successively and cyclically, with respective stages W1, W2,W3, Wn being sequentially put into operative or nonoperative states.

Immediately when a stage becomes nonconductive, the condenser C of thecorresponding stage discharges through a discharge loop formed by adiode D, a load L of the respective stage and a load of the precedingstage. Thus, when the terminal stage Wn is brought into operation, thecondenser C1 of the first stage W1 is charged on the side near to thediode D1. As soon as terminal stage Wn becomes nonconductive, the firststage W1 automatically comes into operation. In this manner, sequentialenergization and deenergization of loads are effected cyclically.

Since the operating time of respective stages depends upon the productof the values of a condenser C and a resistor R, the time intervalbetween energization or deenergization of any particular load may bedetermined by using condensers and resistors of particular values.

If a starting condenser Cs is in every two or more stages: sequentialand cyclical flash operations are effected in multiple ways.

In FIG. 2, a diode is substituted by a resistor, but operation is thesame as described hereinabove. In case the starting condenser Cs isconnected as shown in FIG. 2, the base current of the transistor Trblflows through a loop constituted by the condenser Cs, the resistor Rcl,the transistor Trbl, the line In and the load Ln of the terminal stageWn. Consequently, the collector current of transistor Trbl flows. Inother words, the base current of the transistor Tral flows to raise thecollector potential of transistor Tral. Thus, positive feedback takesplace through a loop comprising the condenser C1 and the resistor Rcl toput the transistors Trbl and Tral into operation.

The sequential flasher of the present invention may be basicallyconstituted by monostable multivibrator circuits arrange arranged incascade connection.

In a general monostable multivibrator circuit which either necessitatestwo sources of electric potential or employs one potential source, thereis a resistor common to an emitter. This disadvantageously causes alarger drop in voltage, or overheating in a transistor, and fails inproducing sufficient output.

The sequential flasher of the present invention represents a substantialimprovement, overcoming the foregoing disadvantages. In addition, thesequential flasher has an advantageous construction and operation, inthat starting in the respective stages is very smooth, a transistor of asucceeding stage is not brought into conduction unless the precedingstage has become nonconductive, while the stage is in a nonconductivestate, both of its transistors remain nonconductive. This minimizespower loss in the respective stages, and such power loss has beensubstantial in the conventional monostable multivibrator circuit havinga transistor which is usually maintained conductive.

We claim:

1. A sequential flasher comprising, in combination, a source of electricpotential; a plurality of successive stages arranged in cascadeconnection and each including a PNP transistor, having its emitterconnected to the positive terminal of said source, and an NPNtransistor; each stage including a first loop constituted by the emitterof the respective PNP transistor, a resistor connecting the base thereofto the collector of the associated NPN transistor, and a resistor andcondenser connected in series between the base of said associated NPNtransistor and the collector of said respective PNP transistor; eachstage further including a second loop constituted by a resistanceconnecting the emitter of said associated NPN transistor to the junctionof said resistor and said condenser; a respective load connected betweenthe collector of each PNP transistor and the negative terminal of saidsource; circuit means connecting the collector of the PNP transistor ofeach stage, except the last stage, to the emitter of the NPN transistorof the next succeeding stage; and circuit means connecting the collectorof the PNP transistor of the last stage to the emitter of the NPNtransistor of the first stage.

2. A sequential flasher, as claimed in claim 1. wherein said resistancein said second loop is a resistor.

3. A sequential flasher, as claimed in claim 1 wherein said resistancein said second loop is a diode.

4. A sequential flasher, as claimed in claim 1, including a startingcondenser connected in parallel with the collectoremitter circuit of theNPN transistor of the first stage.

2. A sequential flasher, as claimed in claim 1, wherein said resistancein said second loop is a resistor.
 3. A sequential flasher, as claimedin claim 1 wherein said resistance in said second loop is a diode.
 4. Asequential flasher, as claimed in claim 1, including a startingcondenser connected in parallel with the collector-emitter circuit ofthe NPN transistor of the first stage.